Single-Cylinder vs. Double-Cylinder Deadbolt Installation: Choosing the Right Fit for Your Door
A single-cylinder deadbolt operates with a key on the exterior and a thumb-turn on the interior — the most common choice for solid, windowless front doors throughout Toronto. It allows quick exit in an emergency without searching for a key, which matters in multi-storey homes where escape time is critical. A double-cylinder deadbolt, by contrast, requires a key on both sides. This is often chosen for doors with decorative glass inserts or sidelights, where a burglar could otherwise break the glass, reach in, and flip a thumb-turn. Double-cylinder units are popular on rear garden doors in neighbourhoods like High Park and Riverdale, where doors commonly feature narrow lite panels. Our technicians walk you through the trade-offs — including the important fire-safety consideration of always keeping a key accessible indoors — before recommending which cylinder type suits your situation.
The installation process itself differs depending on whether your door already has a standard 2-1/8-inch bore hole or an older, non-standard preparation. Many Toronto homes built before the 1970s have doors drilled for smaller or offset hardware, or have a mortise lock pocket routed into the edge of the door. In those cases, our team either adapts the existing preparation or uses a lock that is specifically designed for that door profile. We work damage-free where the door and frame allow, meaning we avoid unnecessary enlargement of existing bore holes and protect the door finish throughout the process.



